The invention relates to a capsule, a system and a method for preparing a predetermined quantity of beverage suitable for consumption using an extractable product.
Systems for preparing a beverage, such as coffee, using a brewing device for supplying a liquid, such as water, under pressure to a capsule comprising a dose of a beverage ingredient are known. Commonly, the brewing device comprises a receptacle for receiving the capsule, such as an enclosing member for enclosing the capsule. In use a sealing engagement is provided between the capsule and the enclosing member, so as to prevent leaking of a liquid, e.g. water or the beverage. The sealing engagement is usually obtained by pressing the capsule and the enclosing member against each other along a circumferential line of contact.
It is possible that the material of the enclosing member at the location of the sealing engagement, e.g. an elastomeric material, is softer than the material of the capsule at the location of the sealing engagement, e.g. aluminum. Such system is for instance known from EP 1 203 554. In such case the material of the enclosing member at the location of the sealing engagement may be compressed. Such systems may have the disadvantage that the material of the enclosing member at the location of the sealing engagement can subject to wear, degradation and/or fouling, so that the quality of the sealing engagement may deteriorate if the age of the brewing device increases.
This disadvantage seems to be, at least partially, overcome by other known systems, wherein the material of the enclosing member at the location of the sealing engagement, e.g. a metal, is harder than the material of the capsule at the location of the sealing engagement, e.g. a plastics material. Such system is for instance known from FR 2 617 389. In such case the material of the capsule at the location of the sealing engagement may be compressed. Such systems have the advantage that the material of the enclosing member at the location of the sealing engagement may be less subject to wear, degradation and/or fouling, while good sealing engagement may be obtained. Especially when the material of the capsule at the location of the sealing engagement is the same material as the material of the circumferential wall, the capsule may be manufactured with great ease. This may, however, provide the disadvantage that such sealing engagement may be upset if the enclosing member, at the location of the sealing engagement, possesses irregularities, such as scratches, crevices, caked-on foul, protrusions or the like.